Combine juice and fish in a zip-top plastic bag; seal. Marinate in refrigerator 2 hours, turning once.
Heat oil in a large skillet over medium heat. Add onion to pan; cook 8 minutes or until tender, stirring frequently. Increase heat to medium-high. Stir in tomato, 2 tablespoons pimiento, capers, chopped jalapeño, and salt. Cover and cook 5 minutes. Add 1/4 cup water and fish; cover and cook fish 3 minutes on each side. Uncover and cook 3 minutes or until fish flakes easily when tested with a fork or until desired degree of doneness. Place 1 fillet on each of 4 plates. Top each serving with 1/4 cup sauce. Sprinkle each serving with 1 1/2 teaspoons remaining pimiento. Garnish each serving with 1 lime wedge.
Wine note: Halibut with Caper Sauce is perfect with a mild-tasting sauvignon blanc, which picks up on the "green" briny flavors of the capers and is delicate enough to match well with the fish. Try Dry Creek Vineyard Fumé Blanc 2005 from Sonoma County, California, about $15. (Fumé blanc is another name for sauvignon blanc.) With its bright, refreshing, limey flavors and clean, pure taste, it's just right for the dish. --Karen MacNeil